The purpose of this study was to investigate the effect of different concentrations of desflurane on jugular bulb gases and jugular bulb pressure (JBP) and to determine an optimal concentration of desflurane in neurosurgical patients with supratentorial tumor. Twenty-two patients were anesthetized with desflurane in oxygen. Radial arterial and jugular bulb catheters were inserted for blood gas sampling and direct blood pressure measurement after anesthesia. Mean arterial blood pressure (MAP), heart rate (HR), and JBP were monitored continuously. Arterial and jugular bulb blood gases were measured at 0.7 minimum alveolar contraction (MAC) (4.2%), 1.0 MAC (6%,), and 1.3 MAC (7.8%) of desflurane randomly after a 30-minute stabilization period, respectively. Jugular bulb oxygen saturation (SJO2) significantly increased and cerebral arteriojugular difference of oxygen content (A(J)DO(2)) and oxygen extraction ratio (O2ER) significantly decreased from 0.7 MAC to 1.0 MAC of desflurane, but there was, no further increase in SJO2 nor further decreases in A(J)DO(2) and O2ER at 1.3 MAC compared with 1.0 MAC desflurane. There was a significant dose-related decrease in MAP from 0.7 MAC to 1.3 MAC of desflurane, but JBP did not change significantly. No significant change in hour was observed in the study. It is concluded that 1.0 MAC is a suitable concentration of desflurane in neurosurgery with an improved balance between cerebral oxygen supply and demand.